For the most part, assays involving the detection of enzyme activity, either for measuring enzyme substrate, enzyme, or the enzyme as a label have depended upon colorometric or fluorimetric detection. However, there has been a continuous and expanding interest in electrical detection using either amperometric or potentiometric methods. These methods require a redox couple which can be detected at an electrode.
There are many constraints in developing a diagnostic system. Compositions must be developed which allow for the transport of electrons from the enzyme or a product of the enzyme. The various materials which are employed must not interfere with each other, so that neither the enzyme reaction, nor the transfer of electrons to the electrode, are adversely affected. Because in many instances the analyte is present in very low concentration, it is important that the individual reaction related to the amount of analyte be very rapid, desirably diffusion controlled. In this circumstance, there will be a rapid response for each enzymatic event.
It is therefore of interest to devise compositions which may be used in the electrical detection of enzymatic reactions, by providing for rapid and efficient transfer of electrons to an electrical sensor as a result of enzymatic reaction.